Refrigeration



29,1935; G. c PEARCE 4 2,018,896

REFRI GERA'I' I ON Filed Oct. 25, 1932' 4 Sheets-Shout 1 G. C. PEARCE Oct. 29, 1935.

REFRIGERATION Filed Oct. 25. 1932 4 Sheets-Sheet 2 294il935. G. c. PEARCE RE RIGE ATION- Filed Oct. 25, 1932 4 Sheets-Shaet 3 rl l a. c. PEARCE REFRIGERATION Filed Oct. 25, 19s2 4 Sheets-Sheet 4 I z 1 I I I r r r less ,PATENr-oFlucE UNITED STATES? mom'rlon Ohi an mby meme ligaments. to Generai'hlotors ct Dela M om 2 5, 1.32.8611! No. 889,481-

sclm' cl. 02-4) [his invention relates to refrigeration and/or starting controls m1- electric-motors. certain types oi. refrlgerstlnl systems operate aermittently, the temperatures are maintained theoblecttobecooledhystartingandstwg the refrigerating system to produce refrig itton intermittently. Other types ot rei'rigera :t to be cooled. In either-case. therein! sting M is toradstmentn dei'rosting, or for transmutation ol -.tions in the atmospheric system includes a continuously open expansion .i'orm of s' bimetallic .U-

I! and through the returnllnelI-to -the compressor i0. Between the condenser II and the evaporator llis an expansion device It. which maintains the necessary'pressure differential between the condenser ii and the-evaporator 5 ll. Preferably this refrigerating system is oil the substantially continuously operating type in which the parts are so'co-reiated with the refrigeration demands oi the object tobecooled that the system inherently maintains the desired tem-' i0 perature in. the object notwithstanding variatznpersture. Such a.

device in the form ota fixed elongated orifice. It

thesystemshouldbestoppedtoranyresson,the15 pressures within-the refrigerating system equalize within a relatively short time such as within one quarter to one half hour.- Sucha system is more particularly described-in the application of Andrew A. Kucher, Serial No. 599,239 filed March 20 16, 1932 to which relerence is hereby made for further disclosure oi such a system.

- The compressor Ills driven by an electric 2 motorllwhichmaybeplacedinahermeticcasflingllawith thecompressonandwhichmaybezo oiythesolltphmtrr v s rotor imerunningwinding ll andastartingwinding II. My improved control sogoverns the flow of'current'tothese windings, that thecurrentflowsto .both windin'gsduring thenecessarynormalstartto ing period 0!- the motor and the currentxis disconnectedirom the starting winding II atterthe termination ot'the normal starting period or the motor. To thisend, as shown in Fig. 1, a commonlesdline itisconnectedtotherunningandto wlndlngs'at ll. e Another lead line Ill starting .-l-Idivided mtoastartinglesdlineii connected" tothestartingwindingatn and'alsointoa running lead'line II connected'to the rimning. winding IQat'the point I. Anelectromagnet llco .ispiaoedintherunningleadlinell a-ndiscon-v nectedby thebranches It and 21 inthe running ieadline.,hshuntlsplacedinthenmning "lead linesothatthe electromagnet "maybe shunted outotthesystemandthlsshuntmaytt include a timing device 2l,-convenlently in the shapedmemberconnectedbytheshuntbranchestlandlloi'the runningleadline. Theelectromagnet-flispromeammmet-income u whiehincludesmesnsso or-eontacts-II and 88 tor opening and-closing Thesrmaturelican 'retraetiromthemsanetflasuiloientdictsnce 'll,suehthatiti's-sttraetedtothemlm tl m ll, but the space 34 is suiiiciently'large that the armature 1 2| and "the starting winding i1.

current in passing through the timing device ll.

3| is not attracted'to thernagnet during the normal current flowing through the running winding it, for any reason, the armature II is permitted once toassume its retracted position. v. j I

In addition, overload device llis. placed in the electric circuit, so that it stops the flow oi! current to-the motor ll. x

. The operation of the system shown in Fig, i is as follows. {when current is first caused to flow through the system, it passes through the lead line iii/the running lead line 23, the running'wlnd ing It, and thecommon lead'line ll. At this time, thecurrentflows through the branches 26 and 21 and the electromagnet 25. The electro- 1 magnet; in response to the starting surge current through the running winding, it, attracts the armature-3|, so that'it pivots about the fulcrum Al and closes the contacts 32 and ll, thus cause ing current to flow through the starting lead line The starting which, in this form, is a bimetallic U-shaped mem ber, causes it to bend to close contacts 42. When these contacts are closed, the electromagnet is shunted out of the circuit, the current flowing through the branches 29, III. a portion 01 the member 28 and contacts 12. The time required for the completion ofthisbending action of the timing device is sufliciently long, so that the con-' facts '42 are not closeduntil after the normal .period'oi' time required for the motor to start.

After this period 01' time, the magnet 25 is shunt- "ed out 01 the circuit and the armature ll retracts from the magnet 25 and opens the contacts I! and 34, thus stopping the flow or current to thestarting-winding l1; Bimetallic member II is so callbrated that when the starting current ceases to now through it, it separates the contacts," and I lead line It. Since the motor thus the current flows to the motor only thromh the lead line 20, the branches I, I1, and'the electromagnet 25, the running winding l8, and the has attained speed, the current flowing through the electromet 26 is only the normal running current and this is insuflicient to attract the armature ii to the magnet 25 after the armature has been permittedto retract by the shunting action heretofore described. Themotor continues-m operate in this manner until it is stopped either by the'pverload device 35, by a thermostatic switch; lie or similar device which controls the refrigerating efl'ect on the system, or by any other automatic or manual switch which may system.

In the modiflcationshown in'Fig. 2, the refrigerating system maybe identical with that shown in Fig. l'and hence corresponding parts aregiven identicalnumbers; The motor II may also be identical with that shown in Fig. 1 and hence its:-

. rotor, running windingand starting winding are T given identical numbers. Inthis modification a common lead line I8 is provided, this being he convenientlyplaced in the .understoodbythoseskiliedintheart] aoiaaeo connected to the running and starting winding: at the point I. Another lead line 20 is provide: having the overload device 35 identical with tha1 described in Fig. 1 including the bimetallic mem-, ber ll and the resistance I1, arm 38,-i'uicrun II, and contacts 48. The starting line lid and the runningleaddine 219 are slightly modified.

The branch ll, timing device I! and branch ll are partsoi' both the running lead line Ila and the starting lead lineiia. From the point ilu on partortherunningleadlineilaincludesthr branch I8, electromagnet i9 and branch leading to the running winding It at 2|. Another part oi the running lead line includes the contacts 53 and the branch 54. The starting lead line Ila includes the branch 60, contacts 6|, I, and the branch 83 leading to the starting winding I1 and 22.

In modification shown in Fig. 2, when the current is first introduced intothe system, it flows through the lead 20, contacts til, resistance 31, branch ll, legs 5!, Bl, branches i1, '5', electromagnet 59, branch 55, rumuns winding l0, and common lead l8. The current flowing through themagnet is attracts the armature i4 piyoted at 68 and closes the contacts I and I2. Gurrent then also flows through these contacts and the branches and Bl to the starting winding l1. Thecurrent flowing through the timing device 52, which at thistime includes the total current required by the starting and running windings under starting conditions is sumcient to cause the, device 52 to close the contacts 53 after the normal starting period of the'motor, andthe device 52 is so calibrated that it will not close these contacts until the motor has started. When the contacts "are closed, the elect'romagnet II is shunted by a flow of current through the leg I.l,'con-' tacts 63, branches SI and 55 to therunning winding. it. When this shunting action occurs, the armature 8| retracts from the magnetand opens the contacts Ii and 62, thus stopping the flow 01 current to the starting winding II. The resistance of the device I2 is so calibrated that the current flowing to the running winding alone under any condition and passing' through the leg-ii alone, or through hoth'lcgs II and I6,'is insumcient to'maintain the device 5! ins. sufllciently heated condition and therefore the contacts I! begin toseparate as soonas therlmningwinding is cut out. when the contacts 83 separate current flows from the line ill through the branch 5| device 52 branches 51 and I8, electromagnet l9 and "branch 55 to the running winding without closing the contacts I, I2, since the magnet II is; so calibrated that it-cannotattract the armature. I. to iteyen with the-highestnormal running current-passingthrough it','but can be attracted by the starting surgecurrent flowing to the running The device I2 is therefore cooled ofl and inreadiness to initiate -a cycle practically as'so'on as the previous starting cycle is ter- In bothmodifications shown in Figs. land2,the cooling action of the timingdevices I! and 82 are i so calibrated with respect to the'cooling laction or the overload device 35, that, should the over-'7 load device 35 open the contacts It, the timing devices 20 and I2 willhave cooled and be in'readi-' ness-to function beforethe overloaddevice i5 7 has cooled and reclosed contacts 40. This is acc'omplished by rnaking the members of the proper relative weight or by proper thermal insulation of the members to accomplish this result, as will be 1 that the source of electric current iails temporarily either because of an electric storm or other causes, but isrestored in a relatively short time. Sometimes failure is of suiiicient length to permit the refrigerating system to equalize as to refrigerant pressures, but at other times the failure is of such a short duration that the refrigerant pressures cannot equalize sufiiciently to unload the compressor II to permit the motor I3 to start. Undoithese conditions. when the current returns, the starting cycle will take place as usual, the current flowing .through both the running winding and starting windings for the normal starting period: but since the motor is unable to-start because of the 'high torque required, the current flowing through both windings during the starting period and the subsequent how of current through the running winding of the stalled motor eventually causes the overload device 33 to open the contacts 33. After the contacts 33 are opened the overload device 33 starts to cool, but requires a longer lengthoftime thanisrequiredby the timing devices 23 or 32 and hence when the overload devi'ce'33 has cooled suiliciently to close the contacts 30, the timing devices 23 and" are in read-' .iness to reinitiate the starting cycle. Another starting cycle will then be completed, and if the compressor still prevents the motor from v starting, another overloading action will occur and thus as many starting cycles will be repeated as required until the refrigerant pressures have equalized sumciently to permit the motor to start.

Since the system equalizes within 3 to minutes, and since each overloading cycle requires from one to two minutes, the number of false starts is not excessive and will not burn out the motor.

The starting control for the motor as described in Figs. 1 and 2 conveniently may be placed in a unitary structure such as shown in Figs. 3 to 7 inclusive, in which the physical embodiment of the controls diagrammatically shown in Figs. 1 and 2 are shown. Conveniently, the starting control structures may be mounted on a base Ill made of insulating material, this base being provided with a cover "I which may be held in place by the bolt I32 passing through both the cover and the base. The base may have protruding benches I33, I33, and "I3 to which various parts of the control can be attached;

Thus portions of the lead line previously described with respect to Figs. 1 and 2 may be made of brass strips and. portions thereofmay be made of insulated wire Joining the brass strips and other members of the control.

On the bench I33 there is placed a brass strip II! but backwardly at I33 and provided with a contact I31 which corresponds to one of the contacts 33 shown in Figs. 1 and 2. The arm I33 may be pivoted on a pin I33, this arm corresponding to the arm 33 of Figs. 1 and 2. and the pin I33 corresponding to the fulcrum 33. This arm may be attracted by a permanent magnet I I3 mounted on the backwardly oifset portion In of i with a head and on' the other with a hat metallic strip Ill with a spring iil interposed between the plate liland the arm I33. The plate Illtact III which is carried by another brass strip I" mounted on the side of the bench I33. The

' strip 'I I1 carries the bimetallic member III which engages the adjustable screw 3 carried by the arm I33. A resistance wire II is also secured to the strip III and to a brass strip I22 mounted on the bench I33a. The strip I22 carries one is adapted to bridge the contact in and the conleg of the U-shaped bimetallic member -I23 while the other leg of the bimetallic member l23- is. attached to a short upward extension I24 of a metal strip I23 which is secured to the base I30. The strip I23 is provided with a wire receiving screw post I23. The strip I23jis also provided with an. upward extension I21 which-carries a contact I23 near thebench Ill3. The bench I33 also carries a brass strip I29 provided with a contact I33 at one end and with a wire terminal screw plug I3I at the other end. The contacts I23 and I33 are bridged by the contacts I32 carriodat one extremity of the armature I33 which is fulcrumed on the end of the brass strip I33.

. Conveniently, the strip I33 is provided with one or morepins I33 which pass through holes or slots I33 in the'armature I33. The, other end I 3| of the strip I34 acts as a stop for the armature I33 and provides the proper gap I33 from the core of the electro-magnet I39, this magnet being mounted on a magnetic L-shaped member I carried by the bench I030. and which carries the magnetic flux from the upper end Ill of the magnet to the proximity of the armature I33, the armature I33 being provided with a cushioning member I32. The U-shaped bimetallic member I23 is provided with a contact I32 adapted to engage a contact I33 carried by the brass strip I which is secured to the bench I33a. and is provided with the wire terminal screw plug I33.

The base I30 carries an extension I33 which has torthe motor and forming connections with the starting and running windings and with their common lead, the ends of the wires of these cables being secured to proper places in the control apparatus 'in order to provide the circuits shown in either Fig. 1 or 2.

In order to connect the structures shown in Figs. 3 to "i to obtain the'cirouit shownin Fig. 2.

one of the wires I33 of the cable passing through I33 is connected to the post'l33 carried by the strip IIl3-. The} other wire I33 of this cable is connected to the post l3l. One of the wires I32 ofv the other cable which passes through the open- 'ing I3! is connected to the post' I3I'. Another wire I33 oi this cable is'connected to the post I33, and'the other wire I33 of the cable is connected to the post I3 I Current flows through the wire I33, strip I33, contact I31, strip 3, contact II3', resistance I2 I,strip I22, bimetallic member I23, strip I23, post L23, wire' I", electromagnet I33, wire I'll. post I33, and wire I33 to the running winding of the motor and returns through the common lead .line I32 to the post I", wire I33, and the main line. The electro-' magnet I33 is so calibrated that the starting surge current flowing through the foregoing circuit including the electromagnet I33 to the running winding causes the armature I33 to spring to its is cut out.

upper position, thus closing the contacts I2l'and I30 to close the starting lead line. Thestarting lead line branches from the strip I25 through the contact I28, armature I22, contact I, strip-I22, terminal ISI, wire I, to the starting winding of the motor and returns through the common lead line or wire I62 to the post Ill, wire IIII to the main line. Thus the flow to the running I and starting windings are substantially simulta-' neous, requiring only the time necessary for the magnet its to attract the armature III. In the meantime the bimetallic strip I23, because of its resistance and the flow through it of the current to both the running and starting windings, has started to heat and'bend towards'the contact I42. After the normal starting period of the motor, the contact Il2 engages the contact I42, which thus shuntstheelectromagnet II! and permits the armature I to drop and open the starting lead and deenergize the starting winding. when the contacts I42 and Ill are brought together and the running winding has been cut out,

the amount of current flowing through the device I23 is reduced to the normal running requirements of'the rimning winding. The device I2! is so calibrated that this current is insuiiicient to maintain the contacts "2, I closed and they begintoopenassoonasthestartingwinding The normal running current than flows through the magnet I, but the magnet is so calibrated that it does not attract the armature I33 under these conditions, and hence the motor continues to run as long as desired with the running winding only.

inordertochangethestructm'eofl igssto 7 so that it may form the circuit-shown in Fig. i. itisonly-ntomovethewire I'llfromthe post I2. to a post III as indicatedby'a dotted line at I'lIIa on the strip I22, the other connecthrough" the wire Ill, strip m, contact m, strip I", contact. Iii, r I20, strip I22, wire I100, electromagnet'lll, wire "I, post I20, and wire I63 to the running winding from whence it returns to the common lead line of wire I 82, post IBI, and wire Ill to the main line. A relatively large or surge current flows through this circuit to the running winding, because the motor is stationary, and the magnet calibration is such that it causes the armature Ill to spring upwardly and the electromagnet I because of the relatively small resistance of the bimetallic member I23. When the electromagnet I3! is shunted, the armature I33 retracts and opens the contacts I2.

and m thus opening the starting lead line and deenergizing the starting winding. when this occurs only the normal running winding current flows through one leg of the bimetallic sh'ip I23,

but the calibration is such that this is insuflicient to heat the strip to the point where it maintains the contacts 2 and I closed and therefore these contacts open. The normal running cur- .rent then passes through th electrnmagnet Ill;

but the-calibration is such thatthis current is not sumcient to move the armature. III upwardly and close the contacts I28 and II The elements of Figs. 8 to 7 inclusive will be readily identified as corresponding to certain ele- 5 meats shown'in Figs. 1- and 2 and need not be vent arcing when the arm I08 is moved.

While in thepreferred embodiment, the tim- 15 1mg devices 2! and 52 are so calibrated that they shunt the electromagnets every time that the motor is started, yet it is within the purview of this invention that'these timing devices can be used merely as protective or safety devices for theso usual surge current starting relay heretofore commonly used. Thus in Fig. 1. the electt 25 may be so calibrated that it attracts the armature II when the starting surge current flowing to the running winding passes through it, but re- 26 leases. the armature because of the decrease incurrent when the motor has attained sufficient speed so that it can attain its normal running condition. This type of starting relay can be calibrated-for the lowest likely voltage to be en- 30 countered during normal operation. Such a relay when so calibrated, however,'is likely to fail to function when unusually high voltages are encountered. When such voltages are encountered, the current flowing to therunning winding does not drop sumciently after the motor has attained its starting speed to release the armature II and thus-the starting winding is not cut out as long as the high voltages continue. The device 2!, under these conditions-of high voltage, can be4o used as a safety device and can-be so calibrated that'it starts to but does not close the contacts 42 under the normal or low voltages heretofore described, but that it will close the contacts 02 after the termination of the normal starting pe- 45 riod and after failure of the armature 3 I to drop during high voltages. Thus under such use of my invention. the timing device 28, while it still does shunt the electromagnet occasionally after the starting period, is used merely as a safety device which closes the contacts 42 only when the voltages are high enough to prevent the armature 2| from functioning normally.

likewise the device 52 of Fig. 2 can be used merely as a. safety device to operate only under 55 the high voltages just described with respect to Fig. i. In this case the electromagnet II can be so calibrated that for low or normal voltages it attracts the armature by the running surge current during the starting period of the motor, so but releases the armature when the running winding current drops after the motor has attained its starting speed. when high voltages are encountered, and the armature it fails to drop, the device 52 responds as a safety device and closes 55 the contacts 52 to shunt the magnet 58 and permit the armature 6 to drop and thus out out the starting winding II. The electromagnet is then unable to reclose the starting contacts even imder such high voltages. It is to be understood that such use of "the timing devices 20 and 52 merely as safety devices as above described comes within the purview of myinvention.

While the form-ofembodiment of the invention as herein disclosed, constitutes a-preferred form,

' whichloliow.

'a,o1e,eee w u as. manner-mm miaht'he tinuously open restricted connection between the condenser and eyaporatortor controlling the new I cl retrigerant'. to the evaporator during the operation ot the ccmpreuor andfor equalizing preaem'ee'within the system to unload the com- -pre'eeonwhenthecompreaeor is idle. .an electric motorandelectriccircuittoroperatingthecom preesor, means in the electric circuit for stopping the enerdaation ot the electric circuit when the pressure! within the closed refrigerant circuit have not equalised sumciently to permit starting of theelectricmotorandatteraperiodoireetagain energizing the electric circuit. and means reeponlire to the temperature'oi the evaporating meantimeentrollingthe energilation o! the electric m. j

'-*--2.-Reirigerating;. acom- 1 preesor, oondenser and evaporator connected in a closed circuit, said cloaedcircuit havinga continuously open restricted connection betweenthe condenser and evaporator torcontrollingtheflowoi refrigerant to the eyaporatorduring the operation oi! the compremor. and tor equalizing pressures within the system to unloadthe compressor when the compressor is idle, an electric motor and electric circuit for operating the compressor, 10 means in the electric circuit for stopping the energizaflon of the electric circuit-when the pressures have not within the closed refrigerant circuit equalized sufllciently to permit starting of the electric motor and alter a period of rest again 15 energizing the electric circuit, and a 'switch for stopping and starting the motor in accordance with the temperature produced by the refrigerating apparatus.

emma c. PEARCE. 

